1. Field of the Invention
The present invention relates generally to agricultural equipment, such as harvesters, and more specifically, to spreader arrangements on such harvesters for spreading agricultural residue such as chaff to a field.
2. Description of the Related Art
An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing and performs a threshing operation on the crop to remove the grain. Once the grain is threshed, it falls onto a grain pan. From the grain pan, the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine.
During the process of harvesting, crop material other than grain (MOG) is intended to be expelled from the combine. This material is usually derived from two areas, the threshing rotor and/or the cleaning system. The material expelled from the threshing rotor is generally referred to as straw and the material expelled from the cleaning system is generally referred to as chaff. This material or crop residue is typically dealt with by spreading or windrowing. Spreading is accomplished using a mechanical device termed a spreader to distribute the straw and/or chaff substantially evenly from the rear of the combine.
The light particle stream called chaff produced by a harvesting operation, is because of its low density and high air resistance, difficult to throw. Current chaff spreaders struggle to spread chaff wide enough for customer demands. Attempts to entrain the chaff with an air stream by introducing airflow into the chaff spreader have met with limited success. A design with an impeller above and a fan below struggled to mix the chaff with the airflow and suffered from high pressure air bleeding out of the fan portion and blowing chaff in an uncontrolled manner.
What is needed in the art is an effective way of generating a controlled air-blast and mixing the chaff with this air blast to provide a compact yet effective spreader for distributing chaff or other crop residue laterally to opposite sides of the harvesting machine.